| 摘要 |
A semiconductor device with a novel structure in which stored data can be retained even when power is not supplied, and does not have a limitation on the number of write cycles. The semiconductor device includes a memory cell including a first transistor, a second transistor, and an insulating layer placed between a source region or a drain region of the first transistor and a channel formation region of the second transistor. The first transistor and the second transistor are provided to at least partly overlap with each other. The insulating layer and a gate insulating layer of the second transistor satisfy the following formula: (ta/tb)×(Era/Erb)<0.1, where ta represents the thickness of the gate insulating layer, tb represents the thickness of the insulating layer, Era represents the dielectric constant of the gate insulating layer, and Erb represents the dielectric constant of the insulating layer.
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